From 1bf11190d56dee51ff4934251ff88eef7dc98ba1 Mon Sep 17 00:00:00 2001
From: Razvan Dimescu <ssaricu@gmail.com>
Date: Sun, 22 Mar 2026 19:36:03 +0200
Subject: [PATCH] reduce network change detection to 5s with tiered polling

LAN IP checked every 5s (cheap UDP socket call). Full upstream
re-detection runs every 30s as safety net, or immediately when
LAN IP changes. Reduces worst-case network switch recovery from
30s to 5s.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 Cargo.lock  |  2 +-
 src/main.rs | 13 ++++++++-----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index cf97456..e50ae9f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -932,7 +932,7 @@ dependencies = [
 
 [[package]]
 name = "numa"
-version = "0.3.0"
+version = "0.3.1"
 dependencies = [
  "axum",
  "env_logger",
diff --git a/src/main.rs b/src/main.rs
index 5de9a15..5c58e24 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -279,14 +279,17 @@ async fn main() -> numa::Result<()> {
 }
 
 async fn network_watch_loop(ctx: Arc<numa::ctx::ServerCtx>) {
-    let mut interval = tokio::time::interval(Duration::from_secs(30));
+    let mut tick: u64 = 0;
+
+    let mut interval = tokio::time::interval(Duration::from_secs(5));
     interval.tick().await; // skip immediate tick
 
     loop {
         interval.tick().await;
+        tick += 1;
         let mut changed = false;
 
-        // Check LAN IP change
+        // Check LAN IP change (every 5s — cheap, one UDP socket call)
         if let Some(new_ip) = numa::lan::detect_lan_ip() {
             let mut current_ip = ctx.lan_ip.lock().unwrap();
             if new_ip != *current_ip {
@@ -296,10 +299,10 @@ async fn network_watch_loop(ctx: Arc<numa::ctx::ServerCtx>) {
             }
         }
 
-        // Check upstream change (only for auto-detected upstream)
-        if ctx.upstream_auto {
+        // Check upstream change every 30s or immediately on LAN IP change
+        // (heavier — spawns scutil/ipconfig, only when auto-detected)
+        if ctx.upstream_auto && (changed || tick.is_multiple_of(6)) {
             let dns_info = numa::system_dns::discover_system_dns();
-            // Use detected upstream, or try DHCP-provided DNS, or fall back to Quad9
             let new_addr = dns_info
                 .default_upstream
                 .or_else(numa::system_dns::detect_dhcp_dns)